The regulation of ion channel expression and trafficking is one means of controlling cellular excitability, but the mechanisms by which cells control channel number and localization are poorly understood. The identification of ion channel in specialized lipid raft domains in the plasma membrane presents a novel means by which ion channel trafficking between the surface and intracellular compartments can be dynamically regulated. The overall goal of the research proposed here is to elucidate the mechanisms by which the surface expression and subcellular localization of Kv2.1 is regulated. The first aim of the proposal is to characterize the Kv2.1-containing endosomal compartment and describe basal trafficking of Kv2.1. This will be accomplished using immunohistochemistry, live cell fluorescence imaging and biochemical assays. Second, the regulatory pathways controlling Kv2.1 trafficking will be investigated. Kv2.1 is a raft-associated protein therefore trafficking assays developed in aim 1 will be used in conjunction with pharmacological approaches to disrupt the raft domain and potential raft-based signaling pathways. The final aim of the proposal seeks to understand the structural determinants of Kv2.1 raft association. Modulation of Kv2.1 trafficking may underlie such physiological responses as the cellular response to hypoxia in the pulmonary vasculature. Therefore understanding of this process will contribute to our knowledge of how membrane excitability is regulated.